When manufacturing pretensioned screw bolt connections, bolt tensioning cylinders frequently are used, in order to apply an exactly defined pretensioning force onto the screw bolts, in particular with large screw bolts from about M16. The screw bolt usually first is put through the aligned through bores in the components to be connected with each other, until the bolt head abuts against the one side of the components to be connected. The screw bolt freely passes through the through bores and with its bolt end protrudes beyond the other side of the components to be connected with each other by a specified measure. Onto this bolt end provided with a thread, a nut is screwed by hand, until it abuts against the component surface. The length of the screw bolt is dimensioned such that in this non-pretensioned condition the bolt end protrudes beyond the nut by a specified length. Onto the bolt end and the nut, a bolt tensioning cylinder now is set, which for example is operated hydraulically and with which the specified pretensioning force is applied onto the screw bolt by lengthening the same. After reaching the specified pretensioning force, the nut is turned down, until it again abuts against the component surface, and then the bolt tensioning cylinder is relieved. Thereafter, the bolt tensioning cylinder is set over to the next screw bolt connection, i.e. to the next screw bolt to be pretensioned.
The connection of the components generally is effected by means of a plurality of individual screw bolt connections. If for example in tank construction cylindrical components are to be screwed together end-to-end, this is usually effected by means of a screwed annular flange connection. From the ends of the cylindrical components, a ring-shaped circumferential flange each radially protrudes to the outside transversely to the cylinder axis, which flanges both are screwed to each other by means of a circumferential row of screw bolt connections. The butt joint and hence the flanges usually extend horizontally, since the components then can be set onto each other without supports transversely to the cylinder axis being required; the bolt ends protrude from the upper side of the flange and the bolt tensioning cylinder correspondingly sits on the upper side of the flange. The working platform for the fitters is arranged such that the flanges lie at waist to chest height of the fitters, so that the same can comfortably mount the screw bolts and nuts in an optimum working posture and also can comfortably actuate the bolt tensioning cylinder. For setting the bolt tensioning cylinder over to the next screw bolt connection, this arrangement however is extremely unfavorable. From a size of M42, the bolt tensioning cylinders have a relatively high weight. The bolt tensioning cylinders either are set over by hand with arms horizontally stretched away from the upper body, which is extremely exhausting. Or a ladder is utilized, in order to be able to grasp the bolt tensioning cylinder from above, which however on the one hand requires the respective fetching and again putting away of the ladder and hence an additional expenditure of time and on the other hand requires a sufficient free space above the bolt tensioning cylinder. What is also conceivable is the use of a crane, which however requires a continuously free space to the top above the screw bolt connections and an extremely high technical expenditure.